Exploring partitions of all boot devices on SP7350 platforms

This document provides a comprehensive overview of the partitions of all boot devices on SP7350 platform.

SPI-NOR flash

SP7350 supports two kinds of root file-system for SPI-NOR flash. One is initramfs (initial ram file-system) file-system and the other is jffs2 (journalling flash file system version 2) file-system.

Initramfs File-System

The initramfs file-system is a RAM-based file system seamlessly integrated into the kernel image. Despite modifications to the root file-system during Linux operations, the kernel image stored in the SPI-NOR flash remains unaffected. This compressed file-system boasts high capacity, providing efficiency in storage utilization for the same root file-system size in flash.

Jffs2 File-System

In contrast, the jffs2 file-system resides in a dedicated partition within the SPI-NOR flash. Any alterations made to the root file-system are committed to the SPI-NOR flash. It's important to note that the performance of the jffs2 file-system may be suboptimal due to the necessity to read and modify the flash.

Partitions

The SPI-NOR flash is partitioned differently based on the file system used: it is divided into 5 partitions when utilizing the initramfs file system and into 6 partitions with the jffs2 file system, as illustrated in the partition diagram of the SPI-NOR flash below:

Please refer to the table below for an explanation of each partition:

Note

For those seeking to adjust partitions, it is crucial to update the definition of the environment variable 'mtdparts' in U-Boot. This adjustment can be made in the header file located at:

boot/uboot/include/configs/pentagram_common_sp7350.h

The existing mtdparts is as follows:

mtdparts=f8000b00.spinor:96k@0(iboot)ro,192k(xboot)ro,128k(dtb)ro,768k(uboot)ro,864k(fip)ro,0x${sz_kernel}(kernel),-(rootfs);

SPI-NAND & 8-bit NAND flash

The SP7350 supports the ubifs (unsorted block image file-system) as the root file-system for both SPI-NAND and 8-bit NAND Flash. Two types of ECC sectors are utilized: the standard 2k sector and the 1K60 sector.

Standard 2k sector

The standard 2k sector consists of 2048 bytes of user data and 28 bytes of parity. As depicted in the figure below, each 512 bytes of user data is accompanied by 7 bytes (56 bits) of parity, capable of correcting up to 4 errors. Notably, a standard 2k sector occupies 2122 bytes of space. Partitions including env, env_redund, dtb, kernel, and rootfs use the standard 2k sector.

1K60 sector

The 1K60 sector comprises 1024 bytes of user data and 105 bytes of parity. It is stored within the standard 2k sector and can correct 60 bits for 1024 bytes of user data, thereby enhancing error correction capabilities. Partitions such as nand_header, xboot1, uboot1, uboot2, and fip utilize the 1K60 sector. As depicted in the figure below, 1024 bytes of raw data and 105 bytes of parity are collectively stored within a standard 2k sector.

Partitions

The NAND flash is divided into 8 partitions, as illustrated in the figure below:

Please refer to the table below for an explanation of each partition:

Note

To adjust partitions, please modify the define MTDPARTS_DEFAULT in the file:

'boot/uboot/include/configs/pentagram_common_sp7350.h'

For SPI-NAND flash:

For 8-bit NAND flash:

Refer to the struct BootProfileHeader defined in xboot/include/nand_boot/nandop.h for the Boot Profile Header.

eMMC device

SD card

Files in boot partition

Refer to table below for files in root directory in boot partition: